window.onload = rolloverInit;

function rolloverInit() {
	for (var i=0; i < document.images.length; i++) {	
		if (document.images[i].parentNode.tagName == "A") {		
			setupRollover(document.images[i]);
		}
	}
}

function setupRollover(thisImage) {  
	thisImage.outImage = new Image();	
	thisImage.outImage.src = thisImage.src;	
	thisImage.onmouseout = rollOut;
		
	thisImage.overImage = new Image();	
	thisImage.overImage.src = "images/"+thisImage.id+"-over.jpg";	
	thisImage.onmouseover = rollOver;
}

function rollOver() {
	this.src = this.overImage.src;
}

function rollOut() {
	this.src = this.outImage.src;
}